157789 Phpbb Bug Fixing.

1. On the main page, correct wrong link. 2. After I added additional forums, the main page only able to display the forums which under the first category. Other forums and category which not under this first category also cannot display at the main page. 3. Remove Who is online at mainpage 4. Remove Statistics at mainpage. 5. Add function to let Admin can edit the date and time of each post.